From the Design of Multifunctional Degradable Epoxy Thermosets to Their End of Life

Abstract

The development of multifunctional epoxy thermosets that meet the requirements of sustainable development by creating new macromolecular architectures, i.e., novel epoxy monomers, is a real challenge. Herein, a bis-imidazolium cycloaliphatic epoxidized room temperature ionic liquid (CEIL) was successfully synthesized at multigrams scale (1−200 g) and used as molecular brick platforms to design various networks combined to a computational approach. Thus, three epoxy networks were developed by cationic polymerization using CEIL and 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (ECC) in the presence of a thermoacid initiator. The CEILbased networks presented higher thermal stabilities (>450 °C) and good mechanical performances combined for promising shape memory behavior. Most importantly, the incorporation of this ionic molecular brick, i.e., CEIL monomer in the architecture of the networks (50% or 100%), addresses the concept "design to degrade" inducing full degradability for the first time under mild working conditions (up to 99.4% of p-CEIL dissolution in 4.5 h).

Theoretical Analysis of Physical and Chemical CO2 Absorption by Tri- and Tetraepoxidized Imidazolium Ionic Liquids

“…Forcefield parameters were taken from the CL&Pol polarizable forcefield for ionic liquid components with OPLS-AA parameters used with polarization added for epoxy, ester, and CO 2 components . The CL&Pol forcefield has previously been shown to accurately simulate experimental properties such as density for base anions and cations used in this study, thus making it ideal to use as a base forcefield to apply. , From the applied forcefield, the density values found by our fundamental and theoretical investigation corroborate the magnitude of density experimentally obtained for a library of imidazolium-based IL monomers, including the tri- and tetra-epoxy monomers bearing the anion NTf 2 – instead of Cl – . − In the current contribution, the densities predicted were 1.24 and 1.28 mg/mL for tri- and tetra-epoxy monomers. Similarly, our co-workers found 1.25 ∓ 0.05 mg/mL and 1.33 ∓ 0.06 mg mL –1 for the identical backbone monomers bearing NTF 2 – as a counterion instead of Cl – …”

From the Design of Novel Tri- and Tetra-Epoxidized Ionic Liquid Monomers to the End-of-Life of Multifunctional Degradable Epoxy Thermosets

“…The tan δ curve profiles indicate the total energy that the materials absorb. In recent work by our group, it was noticed that the introduction of IL monomers into a classical epoxy network significantly increased the amplitude of tan δ max . Herein, the employment of D230 yielded greater amplitudes of tan δ max , which is associated with a greater molecular mobility, meaning that the material can better absorb and dissipate energy.…”

“…This is striking due to the ratio being strongly correlated to SM performance. Our previous report on designing hybrid networks showed that the integration of an IL monomer into a classical epoxy network can increase the G g / G r ratio from 31 to 351, improving the SM performance as a function of IL monomer proportion …”

“…In recent work by our group, it was noticed that the introduction of IL monomers into a classical epoxy network significantly increased the amplitude of tan δ max . 73 Herein, the employment of D230 yielded greater amplitudes of tan δ max , which is associated with a greater molecular mobility, meaning that the material can better absorb and dissipate energy. When PACM and the tetra-epoxidized IL were employed, two alpha transitions were observed, probably associated with inhomogeneous crosslink densities.…”

“…Our previous report on designing hybrid networks showed that the integration of an IL monomer into a classical epoxy network can increase the G g /G r ratio from 31 to 351, improving the SM performance as a function of IL monomer proportion. 73 The onset alpha transition temperatures (T α0 ) and deformation temperatures (T d ) were found from the G′ curves. The T α0 s values were determined using the beginning of the drop of G′ curves, whereas T d s values were obtained from the temperature at which G′ becomes constant.…”